Depends also on what poly you used. I used regular oil based poly on a piece & it took several weeks for the smell to go away. The last thing I built I used ultra-fast drying poly by Minwax - meant for floors. The can says ready to recoat in 2 hrs & walk on in 24. That seemed to cure in a day or so & is smell free next day.
Best stuff I've used as far as smell goes is water based poly (by Behr) ... goes on clear, no smell whatsoever.
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.